Voltage-regulator.



No. 829,826. PATENTED AUG. 28, 1906.

E. F. W. ALBXANDERSON.

VOLTAGE REGULATOR.

APrLIoATIoN Hup MAR.10, 1905.

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'fu S f C1 F g Witnesses. lrwerwto:

Emst T? qlexomde'rson Mm Wy bQMJ/w@ rinirnn enligne rafrnnfr orrronERNST F. YV. ALEXANDERSON, 0F SCHENEGTADY, NEW YORK, SSIGNOR 'lO GENERALELECTRIC CQMPANY, A CORPGRATION OF NEW YORK.

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Specification of Letters Patent.

Patented Aug. 28, 1906,

' Application led March l0, 1905. Serial No. 2119.399.

vTo a/ZZ when?, it 11i/tty concern.- y

Be it known that I, ERNST F. W. ALEXAN- icnnscu, a subject of the Kingof Sweden and Norway, residing at Schenectady, county of Schenectady,State of New York,` have in-V vented certain new and useful Improvements in Voltagedtegulators, of which the following is a specification.

My invention relates to voltage control of alternating-current circuits,and is particularly applicableto the control of the voltage impressedona lamp-circuit on a vehicle propelled by alternating-current motors.

lt is the usual practice to supply the lamps on motor-driven cars ortrains from the power-circuit, connecting the lamps in parallel with themotors. lt is well known that with this connection in starting or onheavy grades when the motors draw a large amount of current the vvoltageimpressed on the lampcircuit may be lowered, so as to decrease thebrilliancy of the lamps to an objectionable extent.

The obiect of my invention is to provide novel means for maintaining thevoltage on the lamp-circuit constant, regardless of iuctuations in theiiow of current in the motorcircuit. lf for this purpose a boostingtrans former is used of the ordinary type in which the secondary-terminal voltage on a non-1n f ductive load, such as a lamp-circuit, isalways in phase with the secondary current, the results obtained are notsatisfactory if the power factor of the motor-circuit is low. This isobvious from the fact that the phase of the secondary current beingdetermined by the phase of the primary 'currentvwill be greatly outofphase with the potential in the power-circuit whenever the powerfactor in the motor-circuit is low, and consequently if the second aryterminal potential is in phase with the secondary current it will not beof the proper phase for most eflicientlyfincreasing the potentialimpressed uponthe lampcircuit. Moreover, the boosting eiii'ect will varygreatly with variation in the power factor. Furthermore, a seriestransformer tends 'to maintain the current in its secondaryproportional,- to the primary current. This is not the eifect desired;but, on the contrary,

it is desired that the transformer should 1mpress a voltage on thesecondary circuit proportional to the pr1marycurrent. ,Iftogam thisresultr the transformer secondany,el is ed heretofore, not only is thesecondary terminal voltage of the wrongephase, as was pointed out above,but also the resistance produces a voltage drop, which impairs theregulation of the secondary circuit if the load in that circuit isvaried.

@ne feature of my invention consists in providing a seriestransformer'for boosting the potential in the lamp-circuit, so arrangedthat the secondary terminal voltage is'substantially in phase with thepotential of the powercircuit, no matter how low the power factor. Atransformer arranged in accordance with my invention has the furtherad-` vantage, as will hereinafter appear, that the voltage drop due tothe lamp-current is substantially in quadrature with the lamp-vot tageand can consequently have very little effect on the regulation of thelamp-circuit whin the number of lamps in circuit is varie Anotherfeature of my invention consists in a novel construction of the seriestrans-y former, whereby its boosting effect may be accurately adjustedin a simple manner.

My invention will best be understood by reference to the accompanyingdrawings, in which Figure 1 shows nections of the motor-circuit,lamp-circuit, and boosting-transformer on a vehicle pro pelled byalternating-current motors. Figs. 2 and`3 are explanatory diagrams. Fig,4 is a side elevation of a series transformer constructed in accordancewith my invention,l and Fig. 5 is a side elevation of the same incross-section.

shunted by a resistance, as has been suggestdiagrammatically the conlReferring to Fi 1'-, represents a drivingi motor for a vehic e adaptedfor operation on alternating currents. I have indicated a motor of asimple series type. For the sake of simplicity only ne motor is shownand all controlling-switches are omitted. The motor M is energized rfromthe trolley-wire W through the trolley T. In the motor-circuit isindicated the vprimary P' of a series trans-4 former. The secondary coilSy is inserted in circuit with the lamps L, which are connect ed inshunt to the motor-circuit. If the ower factor of the motor-circuit islow and 1f the vseries transformer is of the ordinary type in which thesecondary terminal voltage issubstantially in phase withthe secondaryIOO sa senese l current, the secondary voltage will not be of the properphase for most effi ciently boosting the voltage of the lam -circuit.This will be evident from a consideration of Fig. 3.v in

this figure, e represents the phase of the potentia of theVpower-circuit, and c represents the phase of 'the' current through vthemotor-` circuit for a given load andfpower factor. The current throughthe secondary of the 1.0 series transformer will consequently berepresented by the line 'C2 equal and opposite to the primarycurrent c.f'the current C2 is greatly out of phase with the primary oten- 'tiale', as shown, it is evident that lif t 1e secondary terminalelectromotive 'force is in phase with-the current '-.C2 the resultant ofthis electromotive. force".y and the primary electr-emotive force e"will' be much less than the sum of the two electromotive forces, so

zo, that a much greater secondary eleetromotive and, furthermore, avariation in the relative phases of the two component electromotiveforces .will producev a considerable variation in the length of theresultant. N ow if the inductance l is connected across the terminals ofthe secondary winding, as indicated diagrammatically in Fig. 2, thesecondary terminal voltage will not be in phase with the secondarycurrent, but the secondary current will necessarily lag behind theterminal vol- 3 5 tage by an angle somewhat less than ninety degrees,dependent on the relative values of the inductance and the resistance ofthe secondary circuit. Thus with such aconnection as is shown in Fig. 2the line e2 in Fig. 3

-may represent the. hase' of the secondary terminal'voltage. t will beseen that if the secondary winding is so connected that the secondaryvoltage is added to the primary voltage c the resultant e will be verynearly equal to the sum of the voltages e2 and e',

and consegluently the desired boosting effect is obtaine with aboosting-transformer of the minimum size. Furthermore, since the line e2is substantially in line with e a varia- 5o tion of the power factorinthe motor-circuit over a considerable range will )reduce only a veryslight variation in `1e ength of the line e, so that if the transformeris properly adjusted to give the desired phase relations 5 5 for theaverage factor of the circuit the phase relations for all loadconditions in the motorcircuit will be substantially correct, and,furthermore, since the voltage dro in the inductance due to current-flowin t ielamp- 6o circuit is in quadrature with that current it could haveno appreciable effect on the lamp voltage even if the load on thelamp-circuit should be varied.

It is not necessary that an external inductance should be employed for`obtaining the desired phase relations. The. same result can be obtainedby proper design of the transformer itself. By forming the magneticcircuit with an air-gap the same eil'ect'electrically is produced aswith an ii'iductance in shunt to the secondary. A, suitable constructionfor the transformer is shown in Figs. 4 and 5.' In these figures, Mrepresents the magnetic circuit, which is formed with an airgap at itslower end, as indicated atm in Fig. Il. The magnetic circuit M isconstructed of laminations, as shown in Fig. 5, which are pressedtogether betweenclamping-plates rl.I a by the bolts t b. The bolts e atthe to p of the transformer serve also tc secure the magnetic core tosuitable sujiporting members d d.A These upper bolts l) t furthermoreart- ?as pivots, on which the legs of the maggnctic circuit on which thecoils are supported may be adjusted ltoward and away from :ich other.;yFor securing. 'this adjustment the clamping-plates c a are extendedY atthe loweren'ds of the legs, as shown in the drawings, and oppositeplates are connected by 'rods'or 'barsf The two bars f are connected toeach other by a screw-threaded lrod g, 'which is provided with suitablenuts it, by means of which the pivoted legs of the magnetic core may bemoved toward or away from each other, so as to adjust vthe length of theair-gap m, and locked in position. By means of this adjustment thesecondary terminal voltage may be varied in amount rela.

tive to the primary current, so that the proper boosting eil'ect may beobtained `with great eXactness. This adjustment varios to a small degreethe relative phases of secondary current and terminal voltage; but, ashas. already been pointed out, if the secondary terminal voltage-is ofsubstantially the proper phase a considerable shift .in "phase has onlya small effect upon the resuitant voltage in the lamp-circuit.

vWhat I claim as new, and desire to secure by Letters Patent of theUnited States, is--- 1. lIn combination, an alternating-ciirrentmotor-circuit having a low-power factor, a lamp-circuit in shuntthereto, and a transformer having its primary in series with themotor-circuit and its secondary in series with the lamp-circuit yandadapted and arranged. to produce a secondary terminal voltagesubstantially in phase with the impressed voltage in the motor-circuit.

2. In combination, an alternating-current motor-circuit, a lamp-circuitin shunt thereto, and a series transformer having an airgap in itsmagnetic circuit and its primary and secondary windings included in saidmotorcircuit and in said lamp-circuit respectively.

3. In combination, an alternating-current motor-circuit, a lamp-circuitin shuntthereto, a series transformer having an air-gap in its magneticcircuit andits primary and secbndary windings included in. seidmotor-eir Cuit and m said lamp-circuit respectively, and

means for adjusting the length of said air- Y Lifn combinetign, twosingle-phase loadcircuits supplied (in parallel from the seme soureeeJseries transformer having its primary and secondary windings included inseries with said two circuits respectively' :ind having e magnetic Corecomprising@ pivoted member arranged lby its movement to proy seriestransformer having its primary and lnee an. air-gap of Veiieele lengthin said core,

and means for clamping said member in posi-v tion. i

' :5. .in combination, twe single-phase load- Cireuitssupplied inparallel from the seine source, a series transformer having its pri#mary and secondary windings included in ries with said two circuitsrespectively endl having a magnetic eore comprising two piv- -oted legsadjustable toward and away' from each other to produce sin air-gap ol.'variable length 1n sind core, and :in adjustable leelung device fordetermining the length of the .ein

gap,

6. .ln combinntien, an alternating-curfei'it motor-circuit ot variableCurrentA and power taeter, i lamp-circuit in shunt thereto, and eseeondey windings iijieluded in seid motor circuit and in saidlamp-circuit respeetiveiysource, one' of seid. circuits li;

former lnwing its inni?? in series "n.'itii the 4.o nioteneireuitsnd itsseeende. n, series with the lan'ip-eireuit and se erreieeii. that tlieVoltage drop in ,the seconde@ or. sind 't1-'nf s former due to iiow of'f iurrent in e lamp-ei cuit is substantially in qnsdrf 'tue with seidcurrent.

8. in eombiimtion, twe sinffl cuits supplied parallel e--pliase ciri theseme loud 0i' low-powerfactor, end e tre its primary in series withpower factor and. i seeond ry the other circuit end Hap to produce esecondary l tag, Cil.. placed frein the seCendantY @errent by :in elf 5t'gle approximately equal to average in 'le et' lag in tl; eii'euit of-lofsvpower 9. lin'eembinatiorn tw circuits supplied ii souree, and sserie tisii-i"oi'iiier lm'vii'ig; en, air-gap in its magnetic circuiten@ pri mary and seeenrary tt mi in inelueed in ries with seid two nireetiveiy.

Us i". igleqinnse med'- piiielel 'from the sinne

